Suffolk County continues to have the worst measured smog problem in the state, and pollution from soot, diesel exhaust and other sources is on the rise, the American Lung Association has found.
In its annual State of the Air report card released Wednesday, the Lung Association gave Suffolk an "F" for the 13th year in a row for ozone, the primary ingredient in smog.
Nassau County doesn't measure ozone but adjacent Queens County does and received a "D."
"There's very little question in my mind residents in Nassau County are breathing very unhealthy air. The question is how bad is it?" said Michael Seilback, of the American Lung Association of the Northeast.
In 2011, Suffolk monitors recorded 33 days of unhealthy ozone levels for sensitive groups, such as young children and asthmatics. In 2010, 34 days exceeded federal standards.
Ozone, a gas, forms when emissions from factory and power-plant smokestacks and car and truck tailpipes react with sunlight. Inhaling the pollution can cause wheezing, shortness of breath and chest pains, said Luis Rodriguez, a pediatric pulmonologist in Brooklyn and a Lung Association board member. He likened ozone exposure to "a sunburn on the lungs."
While Suffolk's failing ozone grade hasn't changed, air quality in some areas in New York has improved. In 2010, 16 of the 34 counties where the gas is measured got an "F." Only six counties flunked that test last year, the report found.
The report also graded levels of particle pollution, based on data from 2008 to 2010. Those pollutants range from ash and soot to exhaust, chemicals and metals, and can cause serious health problems including cancer.
Suffolk earned an acceptable "B" grade for particle pollution last year, down from an "A" in 2010. Nassau received a "B" both years.
Nationally, 127 million Americans live in counties with poor air quality, said air quality expert Janice E. Nolen, who authored the report. Of those, 3.2 million are New Yorkers.
Areas with heavy traffic tend to have high levels of pollution, though faraway places with coal-fired power plants contribute.
"It's a mixture of both pollution that's being produced locally and blowing over from the Midwest," Seilback said.
To reduce pollution, the Lung Association urges residents to drive less, cut electricity use and avoid burning wood or trash.
Advocates say another threat is the proposed Gasoline Regulation Act of 2012, which would delay tougher tailpipe emission standards.